This invention relates to a link mechanism for an internal combustion engine which is used for a variable valve actuating apparatus that is arranged to vary operation characteristics of engine valve of an intake valve and/or an exhaust valve of an internal combustion engine, and an actuator for a variable compression ratio mechanism which is arranged to vary an actual mechanical compression ratio of the internal combustion engine.
A Japanese Patent Application Publication No. 2011-169152 discloses a conventional variable compression ratio mechanism which uses multi-link piston-crank mechanism, and which is arranged to vary a mechanical compression ratio.
That is, a piston and a crank shaft are connected through an upper link and a lower link. A posture of the lower link is controlled by an actuator including a driving motor and a speed reduction device. With this, a piston stroke characteristic of the piston is varied to control the engine compression ratio.